The following studies on the effects of pollutants on macrophage structure and function are being conducted. (1) The effects of cigarette smoke, manganese dioxide and asbestos fibers on the number and viability of rat alveolar and peritoneal macrophages, (2) the effects of cigarette smoke, managanese dioxide, and asbestos fibers on the fragility of the macrophage lysosomal membrane. The amounts of acid phosphatase, beta-glucoronidase, cathespin - D will be assayed in the supernant from the pollutant exposed cells to determine the degree of disruption of the lysosomal membranes, (3) the inducibility of Aryl Hydrocarbon Hydrotylase in peritoneal and alveolar macrophages exposed to cigarette smoke, manganese dioxide and abestos fibers will also be studied, (4) further studies will include the effects of cigarette smoke, manganese dioxide and asbestos fibers on the ability of peritoneal macrophages to induce the primary in vitro immune response of rat spleen lymphocytes to sheep red blood cells.